Self-sharpening drill bit



March 6, 1934. w. H. VAUGHN SELF SHARPENING DRILL BIT Filed May 26, 1933 NH. Vauj h n INVENTOR. BY 55m.

MGM

ATTORNEYS Patented Mar. 6, 1934 UNITED STATES PATENT OFFICE.

1,949,591 SELF-SHARPENING 1mm. BIT William 'H. Vaughn, Houston, Tex.

Application my 2c, 1933, Serial No. 972,932

9 Claims. (01. 255-91) My invention relates to well drills and more particularly to the type of drill having cutting blades thereon which tend to cut the formation by combined scraping and shearing action.

I In drfll bits of this kind now on the market it isv necessary to more or less frequently withdraw the drill from the hole in order to sharpen the blade so that the drilling may be continued. This necessitates the consumption of a material amount of time to withdraw the drill from a deep hole, and it is an object of my invention to provide a drill bit which will not only cut rapidly while in operation but will tend to remain sharp so that it can be left in the hole for a materially longer period than in the case with the usual bit of this character.

It is another object to provide a drill bit having the cutting edges thereof curyed in such manner that they may easily clear themselves of material during the cutting operation. This particular feature of a. blade I designate as the mold board effect, that is, it is similar in its action to the moldboard on a plow in that the material cut away from the bottom of the hole isslidable along the face of the blade so as to tend to clear the blade.

It is a further object of the invention to discharge the fiushing fluid toward the curved blade in such manner as to assist in clearing the material from the blade.

I also desire to construct the bit so that it tends to center itself in the hole and cut a straight hole which will not deviate materially from the vertical.

In the drawing herewith Fig. 1 shows a top plan view of a drill bit embodying my invention.

Fig. 2 is a perspective view taken in section approximately on the plane 2-2 of Fig. 3.

Fig. .3 is a side elevation of my improved drill certain parts being broken away for greater clearness.

Fig. 4 is a transverse section on the plane 4--4 of Fig. 3.

The head 1 of my bit is approximately cylindrical, the interior 2 being provided with a cylindrical recess to accommodate the flow of flushing fluid. The upper portion of the hollow interior 2 is threaded at 3 to provide a socket for connection with the usual drill collar or tool joint. The lower end of the cylindrical head is tapered downwardly to an apex, as shown at 4, and this tapered wall is provided with an inclined opening 5 on the forward face of each of the blades 6.

The blades 6 previously referred to are formed integrally with the side wall of the bit and extend outwardly away from the head and are curved forward in the direction of rotation of the drill. The upper end 7 of the blade is ta-' pered upwardly and its upper point is somewhat above the longitudinal center of the head 1. Below the tapered portion 7 there is an approximately vertical edge 8 to the blade, the vertical portion terminating toward the lower end of the head. The lower end of the blade is tapered downwardly at 9 to a sharp point 10, which extends materially in advance of the head. As will be seen from the drawing, the middle portion 8 of the blade is curved more decidedly forward along the lower portion 11 of the vertical part of the blade. Also, the forward tapered portion 9 is curved around to form the mold board effect which is an important feature of my invention. This curvature of the blade is disclosed also in Figs. 1 and 4.

Referring more particularly to the drawing, 76 it will be noted that the forwardly curved edge 9 on the blade, which tapers downwardly to the lower end, is curved in such a manner that the outer edge, which scrapes the side of the hole, forms what may be called the gauge surface 12. 80 As this edge wears away on the outer surface it still maintains a sharp edge, particularly along the inclined or tapered portion 9, and if wear occurs during the drilling operation the edge 12 is still a sharp edge so that the drilling may proceed until the Wear upon the blade extends upwardly close to the tapered portion 4 of the head. The bit will then have to be withdrawn from the hole.

It will in some cases be necessary when a new bit is introduced into the hole to ream the previous hole to some extent, but, due to the shape of the lower cutting edge of the bit, this reaming can be accomplished with very little pinching effect upon the blades. My tool is, therefore, adapted also for reaming holes which have decreased slightly in diameter during the drilling operation.

Also it is to be noted that as the flushing fluid engages the curved face of the blade, it is defiected forwardly and does not tend to cut into the well wall in caving formations. The drill is therefore adapted to drill through materials where it is diflicult to prevent the sides of the hole from caving.

As previously noted, the openings 5, discharging the flushing fluid from the inner chamber 2 of the bit head, are inclined downwardly and laterally toward the forward face of the bit. This delivers a stream of water upon the curved mold- 110 board of the blade, thus tending to keep it clear of material and prevent tendency of the bit to ball up.

It will be noted that my'drill is of simple construction which can .be economically furnished to the trade and that it is economical to operate for the reason that it may remain in the hole, tending to sharpen itself and maintain a cutting edge until material wear occurs, before it is necessary to withdraw the same from the hole. This bit cuts rapidly and uniformly and maintains itself approximately vertical in the hole so that a straight hole results. The advantages of this construction will be apparent without further description.

What I claim as new is:

1. A well drill including a hollow, cylindrical head the lower end of which is tapered, a threaded socket at the upper end, a plurality of cutting blades extending laterally from said head, each blade having an upper tapered portion, a lower downwardly tapered portion and an intermediate vertical portion, said lower tapered portion being curved spirally forwardly in the direction of rotation of the drill to form a mold board surface tending to clear itself of material, and watercourses through said tapered portion of the head directed upon said mold board surfaces to assist in keeping the same clear.

2. A well drill including a hollow, cylindrical head, the lower end of which is tapered, a threaded socket at the upper end, a plurality of cutting blades extending laterally from said head, each blade having an upper tapered portion, a lower downwardly tapered portion and an intermediate vertical portion, said blades being curved forwardly in the direction of rotation of the drill, the lower end of 'each blade being relieved on the rearward side to form a sharp cutting end at the apex of each blade, the outer edge of each blade along the downwardly tapered portion being sharpened to engage the side of the hole and to be sharpened by wearing contact therewith.

3. A well drill including a head, a water passage longitudinally thereof, a plurality of cutting blades extending laterally from said head, each blade having an intermediate vertical portion and a lower tapered portion that extends materially in advance of said head, said intermediate and lower portion being curved forwardly in the direction of rotation of said drill and sharpened so as to wear along the outer edge in contact with the wall of the hole and maintain a sharp cutting edge on said blades, and means to discharge flushing fluid from the lower end of said head on to the curved forward face of each blade.

WILLIAM H. VAUGHN. 

